Process for preparing a crystalline uniformly sized granular detergent composition



United States Patent 3,454,499 PROCESS FOR PREPARING A CRYSTALLINE UNIFORMLY SIZED GRANULAR DETERGENT COMPOSITION Larry E. Meyer, Colerain Township, and Richard D. Walker, Wyoming, Ohio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, 21 corporation of Ohio No Drawing. Filed Apr. 5, 1966, Ser. No. 540,181 Int. Cl. 'C11d 9/10, /04, 3/04 US. Cl. 252-109 10 Claims ABSTRACT OF THE DISCLOSURE Process for preparing a crystalline, uniformly sized granular detergent composition containing sodium tripolyphosphate comprising adding granular silicate compounds substantially contemporaneously with a strong base to an aqueous detergent slurry containing an alkali metal trimetaphosphate.

This invention relates to a process for preparing a crystalline, uniformly sized granular detergent composition. More particularly, crystalline, uniformly sized granules are obtained by an improved process which comprises essentially the step of adding a granular silicate compound substantially contemporaneously with a strong base to an aqueous detergent slurry containing an alkali metal trimetaphosphate in the manner described in detail below. The alkali metal trimetaphosphate reacts exothermically with the strong base in the presence of the granular silicate compound and is transformed into tri polyphosate salts which subsequently hydrate. The resulting detergent composition, after water removal by vaporization, is comprised of crystalline, uniformly sized detergent granules containing water-soluble, hydrated tripolyphosphate salts.

The basic process of converting a detergent slurry containing alkali metal trimet-aphosphates to a granular detergent composition containing water-soluble, hydrated tripolyphosphate salts is set forth in Republic of South African Patents 63/25 and 63/ 1994. The basic process as described therein comprises the steps of forming an aqueous precursor slurry containing from about to about 70 weight percent of an alkali metal trimetaphosphate; adjusting the temperature of the precursor slurry to from about 140 F. to about 212 F.; adding a strong base to the precursor slurry to form a final slurry containing from about 1.5 to 3 mole equivalents of hydroxyl ion per mole of alkali metal trimetaphosphate; reacting the alkali metal trimetaphosphate with the strong base thereby converting the alkali metal trimetaphosphate to tripolyphosphate salts; hydrating the tripolyphosphate salts while vaporizing water in the final slurry thereby converting said final slurry into a foamed mass which comprises a detergent composition containing a hydrated tripolyphosphate salt, and thereafter drying said composition further, if necessary.

More specifically, the process described in the above Republic of South African patents utilizes a precursor" slurry, i.e., an aqueous detergent slurry to which the strong base has not yet been added. The precursor slurry is utilized in order to achieve several specific advantages, including, primarily, the achievement of a more uniform distribution of ingredients throughout the detergent prod- 3,454,499 Patented July 8, 1969 ice ucts. The precursor slurry must contain enough water to initially lend fluid properties to the slurry and, ultimately, to hydrate substantially all of the tripolyphosphate salts formed from the reaction of the alkali metal trimetaphosphate with the strong base. The precursor slurry should contain from about 20% to about by weight of the precursor slurry of an alkali metal trimetaphosphate salt and at least about 20% by weight of the precursor slurry of water. It is preferred that the precursor slurry contain from about 20% to about 45% water and from about 20% to about 60% of an alkali metal trimetaphosphate.

Various foaming agents can also be incorporated into the precursor slurry in an amount of from about 0% to about 25 if desired. These foaming agents provide a better foam during the hereinafter described foaminghydration step and this contributes substantially to a more uniform detergent product. Suitable foaming agents are water-soluble soaps, synthetic organic anionic, nonionic, ampholytic and zwitterionic active detergent materials that are generally compatible with the alkali metal polyphosphates in both solutions and slurries.

Generally, the precursor slurry, in addition to contain ing alkali metal trimetaphosphates, water and foaming agents, can contain other ingredients usually desired in detergent compositions, for example, nonfoaming detergent compounds such as anti-redeposition agents, optical brighteners, fl-uorescers, fabric softeners, corrosion inhibitors, colors, anti-bacterial agents, sulfates, inorganic and organic sequestrant builder salts and the like.

The several ingredients added to the precursor slurry are thoroughly mixed, Then, the temperature of the precursor slurry is adjusted to from about F. to about 212 F. At temperatures below 140 F., the desired trimetaphosphate conversion proceeds too slowly. The result is that the slurry is not foamed sufiiciently into a light density cake as more fully described below. At these low temperatures, the resulting reaction product is not particulate enough for use as detergent granules. On the other hand, if the temperatures of the precursor slurry is above 212 F., the physical act of mixing the strong base into the precursor slurry is severely handicapped because the foaming action takes place too quickly after the addition of the strong base.

.After the precursor slurry has been homogeneously admixed and the temperature has been adjusted, a strong base, i.e., from about 1.5 to about 3. mole equivalents of hydroxyl ion per mole of alkali metal trimetaphosphate, is added and mixed into the slurry. These bases can be added in solid form or in a liquid state, The bases that can be utilized in the practice of this invention are all of those relatively strong bases which can cause the formation of sutlicient hydroxyl ions in the aqueous slurry to react with the alkali metal trimetaphosphate. Among the strong bases suitable for use herein are sodium and potassium hydroxide, sodium and potassium carbonate, the alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, and the like. The strong bases that are preferred in the practice of this invention are sodium hydroxide and potassium hydroxide.

Upon addition of the strong base to the aqueous precursor slurry which comprises an alkali metal trimetaphosphate, a two step exothermic reaction takes place, as illustrated below in Equations 1 and 2, during which the trimetaphosphate ring structure is broken and tripolyphosphate salts are formed. Sodium hydroxide and sodium trimetaphosphate are used for illustrative purposes.

l I 5 l ONa Na ONa ONa I-ONa ONa The resulting sodium tripolyphosophate from Equation 2 then combines with water in the slurry to form a hydrate of sodium tripolyphosphate, preferably sodium tripolyphosphate hexahydrate. The above-described exothermic reaction which results in the conversion of an alkali metal trimetaphosphate to hydrated tripolyphosphate salts is hereinafter referred to as the foaming-hydration reaction.

It is distinctly advantageous during the foaming-hydration reaction to maintain the temperature of the slurry at or above the boiling point of water so as to convert some of the Water in the slurry to steam. If, in a particular case, it is desired to use a lower temperature during the foaming-hydration reaction, a low-boiling, completely water-miscible organic solvent such as methanol, ethanol, acetone and the like, can be added to the slurry. The resulting azeotropic mixture of water and the organic solvent boils at a temperature lower than water alone. The steam or the azeotropic vapor, as the case may be, forms discrete bubbles of gas and renders the slurry into a fairly light density foam.

The complete foaming-hydration reaction should take place at temperatures below about 275 F. If higher temperatures are utilized, the newly formed alkali metal tripolyphosphates will undergo undesired hydrolytic degradation to the orthophosphates and pyrophosphates.

During the foaming-hydration reaction, most of the alkali metal trimetaphosphate is converted into tripolyphosphate salts, and the tripolyphosphate salts, in turn, hydrate. As the foaming-hydration reaction continues, the apparent viscosity of the slurry becomes higher and higher until, after a substantial proportion of the free water has either been bound to the tripolyphosphate as water of hydration, or has evaporated, or both, the reaction mixture becomes a solid seemingly wet mass. Generally it can still contain several weight percent of free water, e.g., up to of the product obtained from the foaminghydration reaction can be free water. The term, free water, as used herein is defined to encompass that water which was initially in the precursor slurry and which is present in the particular composition being referred to in an unbound state, (i.e., not present as the hydrate of any of the salts in the composition). The term moisture has the same definition as free water.

The entire foaming-hydration reaction can take place in less than 2 minutes if high slurry temperatures and the preferred strong bases, sodium or potassium hydroxide, are utilized. With the use of lower slurry temperatures and weaker bases, the reaction may take substantially longer, e.g., up to several hours.

The above referred-to wet mass is generally further dried to a desired moisture content, i.e., from about 0% to about 8% free water by weight of the finished product. It can be dried by additional absorption of the free water as the tripolyphosphate hexahydrate or by a subsequent conventional drying operation utilizing an external heat source. Either during or after the above drying operation, the detergent mass is broken into particles or granules. The oversized detergent particles are generally granulated or broken into smaller more uniform particles which have 4- an appealing, symmetrical appearance and which will not segregate in a packaged product.

The foregoing process, While basically an operable one, presents several serious deficiencies. For instance, the foamed wet mass which forms upon the addition of the strong base is rather amorphous and is not comprised of particulate, crystalline, uniformly sized granules. This amorphous physical state causes many processing disadvantages. First, the foamed wet mass of detergent must usually be further dried before even semiparticulate granules can be otbained. Sizing and granulating screens are readily clogged by these semiparticulate amorphous granules. The foamed detergent mass is usually not sufiiciently friable to fracture into crystalline, particulate granules but rather is merely extruded in noodles through the sizing screen. These semiparticulate granules also tend to cling to processing equipment and cause extensive processing problems. Conveyors are often clogged with these granules and these granules must be subjected to special high temperature drying operations before packaging to prevent caking.

According to the present invention, it has surprisingly and quite unexpectedly been discovered that the abovedescribed process can be improved and the deficiencies enumerated can be substantially alleviated by adding a granular silicate compound substantially contemporaneously with the addition of a strong base to a precursor slurry containing an alkali metal trimetaphosphate, said silicate compound being added in a weight ratio of silicate compound to alkali metal trimetaphosphate of from about 0.02: 1.0 to about 2.5: 1.0 and having an SiO :Na O molecular ratio of from about 1:2 to about 2:1 at the time of addition to the precursor slurry.

In its broadest aspects, therefore, this invention comprises the improvement in a process for manufacturing a granular detergent composition comprising the steps of forming an aqueous precursor slurry containing from about 20% to about 70% by weight of an alkali metal trimetaphosphate, from about 20% to about 45% water and from 0% to about 25% of a foaming agent; adjusting the temperature of the precursor slurry to from about F. to about 212 F.; adding a strong base to the precursor slurry to form a final slurry in an amount of from about 1.5 to about 3 mole equivalents of hydroxyl ion per mole of alkali metal trimetaphosphate; reacting the alkali metal trimetaphosphate with the strong base thereby converting the alkali metal trimetaphosphate to tripolyphosphate salts; hydrating the tripolyphosphate salts and vaporizing water in the final slurry thereby converting said final slurry into a foamed mass which comprises a detergent composition containing a hydrated tripolyphosphate salt; said improvement comprising adding and mixing homogeneously into the precursor slurry substantially contemporaneously with the addition of said strong base to said precursor slurry a granular silicate compound, said silicate compound being added in a weight ratio of silicate compound to alkali metal trimetaphosphate of from about 0.02:1.0 to about 2.5 to 1.0 and having an SiO :Na O molecular ratio of from about 1:2 to about 2:1 at the time of addition to the precursor slurry whereby the final detergent composition is rendered crystalline, and particulate.

The term crystalline as used herein to describe the desired detergent composition is used to characterize a composition having a physical form whose attributes are usually associated with crystals, i.e., hard, dry, free-flowing and discrete particles or granules. It is not necessarily used in a narrow technical context to describe a physical phase whose structure is periodic in all three dimensions.

The term amorphous as used herein is also used in a broad sense to describe a composition having a physical form which is amorphous to the eye, that is cohesive, sticky or non-particulate. It is not used necessarily in its narrow technical sense in which context it means lacking any or der in any dimension.

One of the advantages of the improved process of the present invention is that the final detergent granules are more crystalline, more particulate and more uniformly sized than granules not made by this process. A further advantage of this improved process is that the detergent granules manufactured by this process do not cling to processing equipment or clog granulating devices. Another advantage of this improved process is that no free water is added to the slurry with the addition of the granular silicate compound. A still further advantage of this process is that the silicate compound forms nucleation sites at which the detergent granules form. Another advantage of this process is that the final foamed detergent mass is friable and easily fractured into uniformly-sized crystalline granules. Still further advantages and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

The principal point of novelty of the present invention resides in adding a granular silicate compound substantially contemporaneously with a strong base to a precursor slurry comprising an alkali metal trimetaphosphate. Although not wishing to be bound by any particular theory, it is believed that the increased crystallinity and more uniform size of the resulting granules is due to the fact that the silicate compounds are not totally dissolved when the detergent granules begin to form. The undissolved portion of the silicate compounds creates nucleation sites for the formation of detergent granules containing tripolyphosphate which is being formed from the reaction of the strong base with the trimetaphosphate. It is believed that these nucleation sites enhance the formation of crystalline, uniformly-sized granules.

The amount of undissolved silicate which is necessary to render the desired unexpected advantage is not known for certain, nor can it apparently be determined. It is clear, however, that an adequate amount should be present to provide suflicient nucleating sites to result in the formation of a composition having the desired physical properties as described herein. It is believed that at least 0.5% of the final slurry should be comprised of an undissolved granular silicate compound during the foaminghydration step.

The granular silicate compounds that are suitable for use in this invention have a molecular ratio of SiO' :Na O of about 2:1 to about 1:2 at the time of addition to the precursor slurry. The silicate compounds having molecular ratios of Si0 to Na O in the prescribed range can be used either alone or in combination with each other. It is preferred that the silicate compounds correspond to a granular size wherein about 90% of the silicate granules pass through a Tyler Standard mesh screen and about 85% of the granules are retained on a Tyler Standard 65 mesh screen. Within the above range, the silicate compounds dissolve in the precursor slurry in from about 1 to about 8 minutes depending on the concentration and temperature of the slurry. As it is essential to this invention that the silicate compounds be partially undissolved when the granules are forming, care should be exercised in selecting the particular silicate compound most suitable for use under the particular operating conditions being utilized. 1

It is preferred that the silicate compounds used in this invention be substantially anhydrous. It is recognized that silicate compounds, when exposed to the air, will hydrate, at least to some extent. It is intended, therefore, that the term substantially anhydrous as used herein to identify suitable silicate compounds means those containing only small amounts of water of hydration, i.e., less than 20% by weight of the silicate compound and, preferably, less than 5% by Weight of the silicate compound. Although hydrated silicate compounds can be used in this invention, it has been discovered that the substantially anhydrous forms provide more crystalline granules. It is believed that the overall improvement in the detergent granules of the present invention is, at least, partially due to the fact that the substantially anhydrous silicate compounds absorb more of the water from the wet mass as water of hydration, and thus serve better to partially dry the finished detergent granules.

The free water content in the foamed mass before any subsequent drying step should be from 0% to about 20% by weight of the foamed mass. Therefore, it should be understood that the amount of water initially introduced into the process is important. Since the'addition of an anhydrous silicate compound does not contribute to the total amount of water in the process, larger amounts of water can be utilized in adding the other ingredients to the precursor slurry without exceeding this important free water level. Conversely, less water can be utilized in the process and, thereby, facilitate the drying of the detergent mass in the latter steps of the process.

The preferred silicate compound of this invention is a substantially anhydrous sodium metasilicate which has a molecular ratio of Si0 to Na O of about 1:1 and is granular and free-flowing with 99% passing through a Tyler Standard 10 mesh screen and being retained on a Tyler Standard 65 mesh screen.

Since the rate of dissolving of the silicate compound has an important bearing on the formation of nucleating sites, the following information is pertinent. The table below illustrates the average dissolving time of the preferred anhydrous sodium metasilicate in water at various temperatures and concentrations.

TABLE 1.DISSOLVING TIMES FOR ANHYDROUS SODIUM METASILICATE IN WATER Concentration (see) This table illustrates that dissolving time of the metasilicate is decreased with an increase in the temperature of the slurry and a decrease in concentration of metasilicate. It should be recognized that as the SiO :Na O ratio increases, solubility decreases and dissolving times increase and, conversely, as the SiO :Na O ratio decreases, solubility increases and dissolving times decrease. In the operable ranges of this invention, the silicate compounds of this invention dissolve in from about'one to about eight minutes and preferably from about one to about three minutes.

The granular silicate compounds utilized in the process of this invention should be added to the precursor slurry in a weight ratio of granular silicate compound to alkali metal trimetaphosphate of from about 0.02:1 to about 2.5:1. Within this range, improvements in crystallinity of the detergent granules are fully realized. In a preferred embodiment of this invention, a ratio of granular silicate compound to alkali metal trimetaphosphate of from about 0.1:1 to about 0.611 is utilized. By practicing this process within this preferred range, the preferred material balance, alkalinity and detergency formulations are attained in addition to improveing the crystallinity of the finished detergent granules.

In the practice of this invention it is essential that the silicate compound be added substantially contemporaneously with the strong base. As hereinbefore stated, the silicate compound must be, at least, partially undissolved during the foaming-hydration reaction in order for it to provide nucleation sites for the formation of triplyphosphate detergent granules. Thus, it is essential that the silicate compound be added at a point in time that insures that it will not be completely dissolved when the foaming-hydration reaction commences. It is also essential that the silicate compound be present in the slurry in such a condition before the foaming-hydration reaction begins. Enough time for homogeneously admixing the silicate compound into the detergent slurry must be allowed in order to obtain crystalline, uniformly-sized detergent granules. Thus, it is intended that the expression substantially contemporaneously encompass, at the very least, the time required to homogeneuosly mix the silicate compound into a slurry containing an alkali metal trimetaphosphate and, at the most, slightly less than the time required for complete dissolution of any particular silicate compound of this invention being utilized in any particular slurry containing an alkali metal trimetaphosphate. In a preferred embodiment of this invention the silicate compound is added to the slurry within from about 2 minutes before the strong base is added thereto, to about 1 minute after the strong base is added thereto. Within this preferred range, the maximum benefits of the present invention are obtained. In a further preferred embodiment of this invention, from about 1 to about 100 parts of silicones of the wellknown defoaming type per one million parts of the precursor slurry are added to the slurry containing an alkali metal trimetaphosphate before or simultaneously with the addition of the strong base and the silicate compound. The term, silicones, as used herein denotes the active defoamer portion of the silicone product. Generally, silicones suitable for use in this invention may be defined as synthetic compounds containing organic groups and the elements silicon and oxygen. The silicon should be present in sufficient amount to affect the properties measurably. A more complete discussion of silicones, methods of manufacture and silicone-containing products is contained in Fordham, Silicones published by George Neunes Limited in 1960 and McGregor, Silicones and Their Uses published by McGraw-Hill in 1954. Specific examples of defoaming agents which are suitable for use in this invention are the following: Antifoam A, Antifoam B, Antifoam C emulsion. Antifoam AF emulsion and Antifoam FG-lO emulsion. The materials are characterized in more detail in the table below.

cones is particularly valuable in conjunction with the addition of the silicate compounds. Retardation of the initial foaming reaction allows extra seconds for homogeneously admixing the silicate compound into the slurry. Judicious use of this extra time results in a more homogeneous product and, also prevents silicate lumps in the foamed product.

The following specific examples are given in order to further explain and illustrate this invention. These examples are not intended to limit the claims in any manner.

EXAMPLE I A homogeneous precursor slurry was prepared in a stainless steel crutcher by mixing, in parts by weight, 21.8 parts water, 5 1.8 parts of sodium trimetaphosphate and 3.45 parts of a nonionic synthetic detergent. The particular nonionic foaming agent used in this example was Pluronic L-62, the condensate of ethylene oxide with a hydrophobic base formed by condensing propylene oxide with propylene glycol; the molecular weight of the hydrophobic portion was about 1500, while the total molecular weight was about 2500.

In preparing the precursor slurry, the water was first added to the crutcher. The nonionic was then incorporated into the slurry and the sodium trimetaphosphate was added last. The temperature of the slurry was raised to about 150 F. The slurry was thoroughly admixed for about ten minutes and was smooth and homogeneous.

The precursor slurry was transferred to a stainless steel barrel which was equipped with a paddlemixer. The barrel was surrounded by a stainless steel cylinder, open at the top, said cylinder having a volume about 15 times as great as the stainless steel barrel.

With the mixer turned on, 24.6 parts of anhydrous granular sodium metasilicate, i.e., a silicate compound to sodium trimetaphosphate ratio of about 0.47:1, and 16.2 parts of an aqueous solution containing sodium hydroxide were contemporaneously added to the percursor slurry in separate streams to form the final slurry. The sodium metasilicate had an Si0 to Na O ratio of about 1:1. The granular size distribution of the granular silicate was such that 99% passed through a Tyler Standard 10 mesh screen and about 95% was retained on a Tyler Standard mesh screen. When the sodium hy- DEFOAMING COMPOSITIONS Antifoam B Antifoam O Antifoam AF Antifoam FG-lO Property Antifoam A emulsion emulsion emulsion emulsion Percent active defoamer 100% 10% 30% 30% 10%. Chemical or physical type Coirpounded Silicone emulsioiL- Silicone emulsion. Silicone emulsiom. Silicone emulsion.

s icone defoamer, Consistency Syrupy; thixo- Light crearn Medium cream Paste or heavy Light cream.

tropic Specific gravity 0.97 1.0 1.0 1.0 1 003 Color Translucent, gray White Type of emulsifier None Anionic. Suitable diluent do Water Water Water Water.

The silicones perform two major functions. First, the silicones appear to reduce the surface tension of the detergent slurry and thereby facilitate the escape of entrapped air and steam bubbles. The improved result is that the volume of the foamed mass is decreased and the resulting granules are denser. These denser granules are especially suited for the making of detergent compositions in tabletted form.

Secondly, the silicone defoaming agents, if added before the strong base, retard the initial foaming of the slurry when the strong base is added thereto without substantially increasing the reaction time required for the conversion of the trimetaphosphate salt to the tripolyphosphate salt. The reaction time is measured from the time the strong base is added to the slurry until the reaction is completed. This aspect of the addition of silidroxide solution and silicate were added to the percursor slurry to obtain the final slurry, the conversion of sodium trimetaphosphate to sodium tripolyphosphate was begun. More than 0.5% by weight of the final slurry was comprised of undissolved silicate during the foaming-hydration reaction. Within about 30 seconds after the addition of the sodium hydroxide solution and the silicate, the heat of reaction between sodium hydroxide and sodium trimetaphosphate had vaporized water in the final slurry. The bubbles of water vapor foamed the slurry to about 10 times its original volume While the conversion of sodium trimetaphosphate to sodium tripolyphosphate continued. As the tripolyphosphate formed, it hydrated and therefore converted much of the free water into water of hydration. After about two min utes, most of the conversion to sodium tripolyphosphate had taken place, and the foamed detergent mass fell back to about twice the original volume of the final slurry.

The freshly reacted product was crystalline, particulate and free-flowing and felt dry to the touch. About 4% free moisture, however, remained in the product. This free moisture content was removed in a subsequent drying step. The final free water content of the product was negligible. The yield was 100 parts of crystalline, uniformly-sized detergent granules. No clogging problems were experienced on the sizing screens.

EXAMPLE II The equipment and a precursor slurry similar to that of "Example I was utilized in this example. The temperature of the precursor slurry was adjusted to 150 F. With the mixer turned on, 24.6 parts of granular silicate and 16.2 parts of an aqueous solution containing 50% sodium hydroxide were contemporaneously added to the percursor slurry in separate streams. The sodium silicate had an SiO to Na O ratio of about 2:1 and contained 18% water of hydration by weight. The size of the granular silicate was such that 90% would pass through a Tyler Standard 10 mesh screen and about 85% would be retained on a Tyler Standard 65 mesh screen. The reaction took place substantially as described in Example I. More than 0.5% by weight of the final slurry was comprised of undissolved, granular silicate during the foaming-hydration reaction.

After the free water content of the finished granules was reduced to a negligible amount by a further drying step, crystalline uniformly-sized detergent granules were obtained. The final granular detergent contained:

Percent by weight Sodium tripolyphosphate hexahydrate 80.8 Nonionic synthetic detergent 3.45 Sodium silicate having an S102 to -Na O ratio of 2.8:l.0 15.75 Free water Negligible 1 See Example I for more complete definition.

Generally, a minor portion, i.e., from about to about 20%, of the sodium tripolyphosphate is degraded to sodium orthophosphate and sodium pyrophosphate. It should also be noted that the SiO to Na O ratio is considerably higher after the reaction than it was before the reaction. The explanation is that part of the sodium oxide of the silicate composition hydrolyzes to sodium hydroxide and reacts with the trimetaphosphate.

EXAMPLE III Raw materials A B C D E NaLAS paste 16. 34 14. 01 8.17 NaTAS paste 27.80 23.8 13.9 4. 16 15. 43 15. 43

The NaLAS paste was comprised by Weight of 38.6% of a sodium linear alkyl benzene sulfonate anionic synthetic detergent wherein the alkyl chain contained from 10 to carbon atoms with the following distribution of chain lengths: C10, C11, C12, 16.5% C13, C and 0.5% C 47.8% water and 13.6% sodium sulfate. The NaTAS paste was comprised by Weight of 27.7% of sodium tallow alkyl sulfate anionic synthetic detergent, 53.0% water and 19.3% sodium sulfate. The TAE was a nonionic synthetic detergent, i.e., th condensation product of one mole of tallow alcohol and 11 moles of ethylene oxide. The sodium metasilicate was added together with the sodium hydroxide and had an Si0 to Na O ratio of about 1:1 before addition to the slurry and a granular size such that 99% passed through a Tyler Standard 10 mesh screen and about was retained on a Tyler Standard 65 mesh screen. In all cases, the reaction took place substantially as described in Example I. The product was dried to a free water content of about 3% by weight of the finished product. In all cases, more than 0.5% by weight of the final slurry was comprised of undissolved granular silicate compound during the foaming-hydration reaction.

TABLE 3.-FINAL COMPOSITION OF PRODUCTS Products (parts by weight) Composition A B C D E TAE uu 2. 0 7.0 14. 0 14. 0 Sodium tnpolyphosphate hexahydrate... 51. 8 51. 8 51.8 51. 8 51. 8 Free water .0 3.0 3.0 3. 0 3. 0 Silicate solids 5 7. 5 7. 5 7. 5 7. 5 Sodium sulfate- 7. 58 7. 59 7. 6

EXAMPLE IV The equipment and procedure of Example I were utilized in this example. A precursor slurry comprising 3.73 parts of a nonionic synthetic detergent (TAE see Example III), 46.48 parts of sodium trimetaphosphate, 34.41 parts of water and 30 parts silicone (Dow Corning Antifoam A) per million parts of the precursor slurry was prepared. The slurry was homogeneously admixed and heated to F. With the mixer turned on, 27.27 parts of anhydrous granular sodium metasilicate, as hereinbefore defined, and 5.98 parts of granular sodium hydroxide were simultaneously added to the precursor slurry. The reaction took place substantially as described in Example I except that the initial foaming reaction did not start until about 45 seconds later than the reaction described in Example I. More than 0.5% by weight of the final slurry was comprised of undissolved silicate during the foaming-hydration reaction. The crystalline detergent composition was obtained in the form of large agglomerates. The composition was dried to a free water content of about 3%. The resulting, dried agglomerates were friable and easily granulated with a Colton granulator using a Tyler Standard No. 8 mesh screen. No clogging problems were encountered. The product was further dried after being sized in the above fashion.

EXAMPLE V Two homogeneous precursor slurries were prepared in a stainless steel crutcher utilizing the raw materials shown in Table 4 with the exception of the silicates and the sodium hydroxide solutions. The primary difierence between Product A and Product B is that Product A is made by the process of this invention and Product B s not. The composition of the two products are, otherwise, identical.

Sodium trimetaphosphate Sodium metasilicatc Sodium silicate solution (44% Trisodium uitrilotriacetatc Sodium hydroxide solution- 20. 63 12. 60

Total 128. 49 45. 71

C LAS is sodium linear alkyl benzene Sulfonate having an alkyl chain of about 12 carbon atoms. CNE is the condensation product of one mole of coconut alcohol with 6 moles of ethylene oxide. Sodium metasilicate is a substantially anhydrous silicate compound having an SiO :Na O molecular ratio of about 1:1. The size of the granular metasilicate was such that 99% passed through at Tyler Standard mesh screen and about 95% was retained on a Tyler Standard 65 mesh screen. The sodium silicate solution is an aqueous solution containing 44% by weight of a sodium silicate compound having an SiO :Na O ratio of 2.0210. The sodium hydroxide listed in Table 4 is an aqueous solution containing 50% sodium hydroxide by weight. Water in the sodium hydroxide solution shown in Table 4 is calculated on a sodium oxide basis. The precursor slurries were transferred to equipment similar to that described in Example I. The temperature of the precursor slurries was adjusted to 170 F. The sodium hydroxide and the sodium silicates Were added substantially contemporaneously in separate streams to the precursor slurries. The reactions took place substantially as described in Example I. More than 0.5% by weight of the final slurry of Product A was comprised of undissolved, granular silicate compound during the foaming-hydration reaction.

Product A, immediately after the foaming-hydration reaction, was comprised of a friable foamed detergent mass which was easily broken into crystalline, uniformlysized granules which were free flowing and felt dry to the touch. By contrast, Product B was comprised of a more amorphous denser detergent mass and felt damp. It was apparent from comparing the two detergent masses of Product A and Product B that Product B was not as particulate and crystalline or as friable as Product A; the granules of Product B were amorphous and sticky.

Product A and Product B were allowed to dry in the air for 41 hours. At that time, both products were separately granulated with a Tyler Standard No. 8 mesh screen. Portions of the resulting granules of the respective products were then used to run caking tests.

Caking tests are designed to measure the amount of force required to fracture a detergent cake. A higher force or caking grade, therefore, indicates that the granules are stickier and more amorphous while a lower caking grade indicates that the granules are more crystalline and particulate.

The caking tests were performed in the following manner. Detergent cakes were made from, respectively, portions of the granules of Product A and Product B. The detergent cakes were made with an apparatus consisting of a base plate having a solid, upwardly-extending, cylindrical piston with a diameter of 2 /2 inches mounted thereon. A close fitting cylindrical sleeve surrounded the upper portion of the piston and extended for 2 /2 inches above the top of the piston. The sleeve was then locked in this position. The space above the piston which Was enclosed by the cylindrical sleeve was then filled with detergent granules. A light plastic plate was then centered over the top of the sleeve and a five pound weight was placed thereon. The sleeve was gently unlocked and the weight was allowed to compress the granules into a detergent cake for 60 seconds. Then the weight was removed and the sleeve was pushed down the piston by hand. The detergent cake remained on top of the piston with the plastic plate covering the upper surface of the cake. A mechanical force was then applied downward in the middle of the plastic plate and this force was measured with a mechanical force gauge. The downward force in pounds equals the caking grade. A diiference of 0.5 pound is a significant difference in this test.

The results of caking tests run, respectively, with granules of Product A and granules of Product B indicated that Product A had a caking grade of 4.2 while Product B had a caking grade of 5.0. This test indicated that the detergent cake of Product A was more friable and the granules of Product A were more crystalline and particulate than were the corresponding detergent cake and granules of Product B. Product A contained about 4% free water while Product B contained about 5% free water.

The granules of the respective products were then packed in plastic bags until 112 hours had elapsed from the time they were made. At this time, caking tests were again performed. The differences in caking grades between the respective products were even more apparent at this time. The caking grade of Product A was 2.95 while the caking grade of Product B was still 5.0. Product A contained about 2% free water and Product B still contained about 5% free Water. These comparative tests indicate that Product A continues to absorb free water from the product, probably as water of hydration and, thus, the granular product becomes even more crystalline and particulate with the passage of time.

Granules of the respective products which had been dried for 41 hours were screened to ascertain the size distribution of the granules. The granules of Product A were more uniformly sized.

l Fines 2.3%. 2 Fines 5.9%.

It should be noted from Table 5 that Product B contained twice as many fines as did Product A, the product made by the process of this invention. Fines are highly undesirable in granular detergent compositions as they segregate in the packaged product and produce an aesthetically undesirable image.

The silicate compounds employed in the present invention in the amounts hereinbefore set forth are compatible with all of the ordinary detergent additives. Among the organic surface active detergent compounds which can be successfully utilized in the aqueous precursor detergent slurries of this invention as foaming agents are the following.

(a) Water-soluble soap: Examples of suitable soaps for use in this invention are the sodium, potassium, a1n. monium and alkylammonium salts of higher fatty acids (C C Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium and potassium tallow and coconut soap.

The other suitable detergent substances are outlined more at length as follows:

(b) Anionic synthetic non-soap detergents can be broadly described as the water soluble salts, particularly the alkali metal salts, of organic sulfuric reaction products having in their molecular structure an alkyl radical 13 containing from about 8 to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. (Included in the term alkyl is the alkyl portion of higher acyl radicals.) Important examples of the synthetic detergents which form a part of the preferred compositions of the present invention are the sodium or potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (Cg-C18 carbon atoms) produced by reducing the glycerides of tallow or coconut oil; sodium or potassium alkyl benzene sulfonates, in which the alkyl group contains from about 9 to about 15 carbon atoms, including those of the types described in United States Letters Patent Nos. 2,220,099 and 2,477,383 (the alkyl radical can be a straight or branched aliphatic chain); sodium alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium or potassium salts of sulfuric acid esters of the reaction product of one mole of a higher fatty alcohol (e.g., tallow or coconut oil alcohols) and about 1 to 6 moles of ethylene oxide; sodium or potassium salts of alkyl phenol ethylene oxide ether sulfate with about 1 to about .10 units of ethylene oxide per molecule and in which the alkyl radicals contain from 8 to about 12 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example,, the fatty acids are derived from coconut oil; sodium or potassium salts of fatty acid amide of a methyl tauride in which the fatty acids, for example, are derived from coconut oil; and others known in the art, a number being specifically set forth in United States Letters Patent Nos. 2,486,921, 2,486,922 and 2,396,278. Other important anionic detergents, sulfonated olefins, are described in the copending application of Phillip F. Pflaumer and Adriaan Kessler entitled, Detergent Composition, Ser. No. 524,364 filed Dec. 23, 1965.

(c) Nonionic synthetic detergents can be broadly defined as compounds produced by the condensation of 'alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

As an example, a class of nonionic synthetic detergents is made available on the market under the trade name of Pluronic. These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The hydrophobic portion of the molecule which, of course, exhibits water insolu-bility, has a molecular weight of from about 1500 to 1800. The addition of polyoxyethylene radicals to this hydrophobic portion tends to increase the water solubility of the molecule as a whole and the liquid character of the product is retained up to the point where the polyoxyethylene content is about 50% of the total weight of the condensation product.

Other suitable nonionic synthetic detergents include:

(1) The polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols having an alkyl group containing from about 6 to 12 carbon atoms in either a straight chain or branched chain configuration with ethylene oxide, the said ethylene oxide being present in amounts equal to to 25 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds may be derived from polymerized propylene, diisobutylene, octene, or nonene, for example.

(2) Those nonionic synthetic detergents derived from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine. For example, compounds containing from about 40% to about 80% polyoxyethylene by weight and having a molecular weight of from about 5,000 to about 11,000 resulting from the reaction of ethylene oxide groups with a hydrophobic base constituted of the reaction product of ethylene diamine and excess propylene oxide, said base having a molecular weight of the order of 2,500 to 3,000 are satisfactory.

(3) The condensation product of aliphatic alcohols having from 8 to 22 carbon atoms, in either straight chain or branched chain configuration, with ethylene oxide, e.g., a coconut alcohol-ethylene oxide condensate having from 5 to 30 moles of ethylene oxide per mole of coconut alcohol, the coconut alcohol fraction having from- 10 to 14 carbon atoms.

(4) The ammonia, monoethanol and diethanol amides of fatty acids having an acyl moiety of from about 8 to about 18 carbon atoms. These acyl moieties are normally derived from naturally occur-ring glycerides, e.g., coconut oil, palm oil, soybean oil and tallow, but can be derived synthetically e.g., by the oxidation of petroleum, or by hydrogenation of carbon monoxide by the Fischer- Tropsch process.

(5) Long chain tertiary amine oxides corresponding to the following general formula, R R R N 0, wherein R is an alkyl radical of from about 8 to about 18 carbon atoms, and R and R are each methyl or ethyl radicals. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of amine oxides suitable for use in this invention include dimethyldodecyl amine oxide, dimcthyloctylamine oxide, dimethyldecylamine oxide, dimethyltetradecylamine oxide, dimethylhexadecylamine oxide.

(6) Long chain tertiary phosphine oxides corresponding to the following general formula RRRP O wherein R is an alkyl, alkenyl or monohydroxyalkyl radical ranging from 10 to 18 carbon atoms in chain length and R and R" are each alkyl or monohydroxyalkyl groups containing from 1 to 3 carbon atoms. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of suitable phosphine oxides are: dodecyldimethylphosphine oxide, tetradecyldimethylphosphine oxide, tetradecylmethylethylphosphine oxide, cetyldimethylphosphine oxide, stearyldimethylphosphine oxide, cetylethylpropylphosphine oxide, dodecyldiethylphosphine oxide, te'tradecyldiethylphosphine oxide, dodecyldipropylphosphine oxide, dodecyldi (hydroxymethyl) phosphine oxide, dodecyldi (Z-hydroxyethyl) phosphine oxide, tetradecylmethyl-2-hydroxypropyl phosphine oxide, oleyldimethylphosphine oxide,'and 2-hydroxydodecyldimethylphosphine oxide.

(d) Ampholytic synthetic detergents can be broadly described as deri=vatives of aliphatic secondary and tertiary amines, in which the aliphatic radical may be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic Water solubilizing group, e.g., carboxy, sulfo, sulfato, phosphato, o-r phosphono. Examples of compounds falling within this definition are sodium-3-dodecylpropionate and sodium-Z-dodecylarninopropane sulfonate.

(e) Zwitterionic synthetic detergents can be broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radical may be straight chain or branched, and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfo, sulfato, phosphato, or phosphono. Examples of compounds falling within this definition are 3- (N,N-dimethyl-N-hexadecylammonio) propane 1 sulfonate and 3-(N,N dimethyl-N-hexadecylammonio)-2-hydroxy-propane-l-sulfonate which are especially preferred for their excellent cool water detergency characteristics.

The soap and non-soap anionic, nonionic, ampholytic and zwitterionic detergent foaming agents mentioned above can be used singly or in combination in the prac- 15 tice of the present invention. The above examples are merely specific illustrations of the numerous detergents which can find application Within the scope of this invention. Other foaming agents within the prescribed classes can also be used.

The detergent slurries utilized in this invention may, if desired, also contain materials which make the product more attractive or more effective. The following are mentioned merely by Way of example. A soluble sodium carboxymethylcellulose can be added in minor amounts, e.g., to about 2%, to inhibit soil redeposition. A tarnish inhibitor such as benzotriazole or ethylene thiourea can be added in amounts up to about 2% by Weight of the finished product. Brighteners, fluorescers, bactericides, colors and perfumes can also be included in minor amounts in this detergent formulation. Sodium sulfate," detergency builders ofboth the inorganic and ."gent com positions'l"Indeed 'the process described herein .can 'be' utilized' fd'r themanufacture of crystalline, uni- ..-formly-siz ed, practically"pure, low bulk density, by

drat'e'd alkali metal tripolyphosphate compositions that iri'turn can beutilized as raw materials in conventional processes for manufacturing detergent products.

"The foregoing description of the invention has been presented describing certain operable and preferred embodimnts. It is not intended that the invention should be so'limited since variations and modifications thereof will be obvious to those skilled in theart, all of which E are within the spirit and scope of this invention.

What is claimed is: y

1. In a process for manufacturing a granularldetergent composition comprising the steps of forming an aqueous precursor slurry containing from about 20% to about 70% by weight-of an alkali metal trimetaphosphate, from about 20% to about 45% water and from'0% to'about 25% of a foaming agent; adjusting the temperature of the pre- .cursor slur'ryto from abou t*140 F. to about 212 F.,

adding a strong base selected from the group consisting .uzofpsodium hydroxide, potassium hydroxide, sodium carfibonate, potassium'carbonate, c'alciumhydrox'ide, and magnesiuinfhydroxide to the-precursor slurry to form a final slurry in an amount 'of'fromab'out 1.5 to about 3 mole equivalents of hydroxyl ion per mole of 'alkali metal trimetaphosphate; reacting-the alkali metal trimetaphosphate 1.

with the strong base thereby converting the alkali metal 't'rimetaphosph'ate to tripolyphosphate salts; hydrating the "tripolyphosphate salts and 'vaporiz'ing water inthe fiinal slurry thereby. converting said final slurry into a'foamed 6. H and mixing it homogeneously into the precursor slurr substantiallycontemporaneously with the additioirpf said strong base, wherein substantially contemporaneously is, at the'very least, the'time required to homogeneously mix the granular silicate compound; into the final slurry containing an alkali metal trinietaphosphat'e and, at the most, slightly less than the time required for complete dissolution of the granular silicate compound in the final slurry, said silicate compound b'ein'g added in a weight 'ratio of silicate compound to alka'li metal'trime'ta'pho'sphate of fromabout 0.02: 1.0 to about 2.5 1.0 and having an SiO :Na O molecular ratio of from about 1:2- tojabout 2:1 at the time of addition to'the'precursor slurry whereby the fiinal detergent composition is rendered crystalliiie'a'nd particulate. I p 2 The process of claim 1 wherein'the granular sillcatie compound is substantially anhydrous- 3. The process of-claim 1 wherein the silicate compound has an SiOyNa O molecular ratio 'of about lz'll" 4. The process of claim 1 wherein theratio'of grammar silicate compound to alkali metal trimetaphos'phate is from {about 0.1:1 to about 0.6:1. 5. The process of claim 1" wherein the granular silicate compound has a'particle size distribution such that about of said granular silicate compoundp asses through a T ylei" Standard 10 mesh screen' a'nd about 85% of said '65 mesh screen. 3

6. The process of claims wherein the granular silicate compound has a particle size distribution such that about 99% of said granular silicate compound passes through a Tyler Standard 10 mesh screen and about of said granular silicate compound is retained on a Tyler Standard 65 mesh screen. I "7. The process of claim 1 wherein the granular silicate compound is added to said slurry within from about 2 minutes before 'to about 1 minute after theaddition of said strong base. 7 8. The process of claim 1 wherein from about 1' to about 100 parts of siliconesper one-million parts of said granular silicate compound is retained oiia TylerStandar'id slurry are added to said slurry-before or simultaneously with said strong base, g

9. The product' produced by the process of claim 1. -10. The product produced by the processrof claim .'f j: g I 7 References Cited UNITED STATESWATQENTSQ'" 3,200,080 8/19'65. ;Martin Chill, h; 252 358 3,325,413 6/1967 Novak .252 35 LEON D. ROSDOL Primary Examiner. v i :1:

B. BETTIS, Assistant Examiner. 4 US. 01. XJR. 23- 106; 252-135, 137, 138 I 

